Modification of Nafion® Membrane via a Sol-Gel Route for Vanadium Redox Flow Energy Storage Battery Applications

Nafion 117(n-117)/sio2-so3h modified membranes were prepared using the 3-mercaptopropyltrimethoxysilane (mptms) to react with h2o2 via in situ sol-gel route. basic properties including water uptake,contact angle,ion exchange capacity (iec),vanadium ion permeability,impedance,and conductivity were measured to investigate how they affect the charge-discharge characteristics of a cell. furthermore,we also set a vanadium redox flow energy battery (vrfb) single cell by the unmodified/modified n-117 membranes as a separated membrane to test its charge/discharge performance and compare the relations among the impedance and efficiency. the results show that the appropriate amount of sio2-so3h led into the n-117 membrane contributive to the improvement of proton conductivity and vanadium ion selectivity. the permeability was effectively decreased from original 3.13 × 10-6 cm2/min for unmodified n-117 to 0.13 × 10-6 cm2/min for modified membrane. the iec was raised from original 0.99 mmol/g to 1.24 mmol/g. the modified membrane showed a good cell performance in the vrfb charge/discharge experiment,and the maximum coulombic efficiency was up to 94%,and energy efficiency was 82%. in comparison with unmodified n-117,the energy efficiency of modified membrane had increased more than around 10%. © 2017 shu-ling huang et al.